102 THE ACUTE SELF-LIMITED INFECTIONS 



world help to explain the sudden and otherwise inex- 

 plicable outbreaks of diphtheria, and the difficulties 

 of their eradication. To disinfectants they present 

 a slightly greater resistance than most non-spore- 

 bearing bacilli. Carbolic acid, 1 to 100, kills in ten 

 minutes; corrosive sublimate, 1 to 1000, in twenty 

 minutes. Hydrogen peroxide kills them rather easily. 

 These figures are for bacteria suspended in water. 



Diphtheria bacilli will kill most experimental 

 animals, but the guinea-pig is the most susceptible. 

 Here they characteristically produce a sloughing at 

 the site of inoculation, a peritonitis, and a congestion 

 of the adrenal gland. Sometimes organisms suggestive 

 of diphtheria bacilli are found in the throat without a 

 membrane. In order to prove if these be true diph- 

 theria forms, some of a culture is injected under the 

 skin of a guinea-pig. If the changes described are 

 produced, and the animal dies in three days, it shows 

 that the organism in question was a true virulent 

 diphtheria bacillus. 



Diphtheria Antitoxin. The specific poison of the 

 organisms and the means used to neutralize it must 

 now be discussed. The poison of the diphtheria bacillus 

 is not only made in the false membrane in the human 

 case, but is elaborated by the organism in artificial 

 media in a laboratory. This poison itself will kill the 

 lower animals. The toxin is obtained by growing the 

 germs on broth, made in a manner found most suitable 

 for its development. The broth is freed of bacterial 

 bodies and injected into horses. This animal is chosen 

 for its size and freedom from disease affecting 

 humans, and because large quantities of material may 



